Intermittent gas-lift control



Feb. 11, 1941.

INTERMITTENT GAS-LIFT CONTROL Filed Oct. 21, 1939 A. W. STEENBE RGH I lnvemor: Alexander Wilhelmus Sre nberqh by his Ahorne Patented Feb. 11, 1941 INTERDIITTENT GAS-LIFT CONTROL Alexander Wilhelmus Steenbergh, The Hague, Netherlands, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application October 21, 1939, Serial No. 300,591 In the Netherlands November 10, 1938 7 Claims.

This invention relates to a device for controlling the intermittent supply of compressed gas to gas-lift pumps, and is more particularly concerned with a device in which the gas supply is I controlled by a valve actuated by a movable element or diaphragm exposed to a periodically fluctuating gas pressure in an auxiliary tank.

In mostsgas-lift devices the duration of the working period, that is, of the time during which gas is supplied to the gas-lift pump, is independent both of fluctuations in the pressure of the gas supply and of variations in the quantity of well liquid being raised. Thus, the working period is generally longerthan necessary, and the gas consumption is higher than the optimum.

It has also been proposed to regulate the gas inlet by employing a device to open the supply of gas when a predetermined pressure has been built up in the gas column leading to the gaslift pump or in an auxiliary tank.

However, such systems have the disadvantage that when several of these devices are connected to one source of pressure gas, the working periods of the individual devices may overlap, which may cause violent pressure fluctuations throughout the system.

To avoid this drawback, central gas distributors have been used, which cause the valves controlling the flow of pressure gas to individual wells to open and close in series, so

working periods do not coincide.

A disadvantage of known devices of this type is that irregularities in their operation affect a great number of gas-lift pumps, which may result in serious production losses.

It is, therefore, an object of the present invention to overcome these various drawbacks by providing a reliable gas supply regulator and central gas distributor capable of independently 40 operating the individual gas-lift pumps, thereby insuring an economical consumption of pressure gas.

It is another object to provide a device for the above purpose which has a low initial cost and is readily installed.

Briefly, these and other objects are attained by the present device wherein a valve in the line supplying gas to the gas-lift pump is controlled by fluctuating pressures acting on a movable element or diaphragm in an auxiliary tank to which gas is supplied from the main gas supply through a throttling orifice or supplied intermittently by automatic means, and which tank is provided with'a valve adapted to open to a spaceof low pressure, such as the atmosphere, due to the force that the exerted by the liquid rising in an eduction tube acting on a diaphragm operatively attached to said valve.

The present invention will be more clearly understood from the following description of a pre- 5 ferred embodiment taken with reference to the drawing, wherein:

Figure -I is a diagrammatic vertical section of a preferred embodiment of the present invention. Figure II is a diagrammatic vertical section showing in detail a preferred modification of the central gas distributor of the present invention.

Figure 111 is a diagrammatic plan view showing an embodiment of the central gas distributor as associated with a number of control valves. 15

Referring to Figure I of the drawing, the control device is described in relation to a pump having a displacement chamber and an eduction tube, although the presentdevice may be applied equally well to other intermittent gas-lift pumps. 20

In a'borehole l is placed a casing 2 having a perforated liner 3 attached to the lower end thereof. Depending within the casing 3 is a tubing string 4 having at the bottom thereof an enlarged portion forming a displacement chamber 5. An inwardly-opening check valve 6 is provided in the lowerportion of chamber 5 to permit well liquid to accumulate therein. Extending downwards through the tubing string 4 and into the displacement chamber 5 is an eduction tube 1. In operation, liquid from the producing formations surrounding the borehole is allowed to flow through the perforations of the liner 3 and into the chamber 5 through the check valve 6 when the pressure in chamber 5 is sufliciently reduced; the accumulated liquid is then lifted through the eduction tube 1 by compressed gas supplied from a gas supply pipe 8 to the annular space 9 between the tubing string 4 and eduction tube 1; the check valve 6 in the lower portion o f the chamber 5 closes to avoid applying-high pressures to the producing formations, which may cause production losses; the well liquid and the gas raising said liquid is discharged from the eduction tube 1 through discharge line ill attached thereto at the well head.

To effect this operation of the elements described or their equivalents, which, in combination, may be referred to as a gas-lift pump, the pressure gas or working fluid supplied to the system from a high pressure line I5 is alternately admitted into the pipe 8 and shut off therefrom by means of an automatic valve IS. The valve I6 is pressed into closed relationship with its seat ll by means of a coil spring I 8 and by the 55 .The tank 2| is provided with a discharge valve 3|! which is forced onto its seat 3| by means of 15 a spring 32 and by any excess gas pressure in said tank. A casing 33, as shown, below the valve 30 and about the valve stem 33 is provided with discharge ports 33 which open to the atmosphere. Likewise, any other suitable discharging ar- 20 rangement may be used; for example, conduits may be connected to the discharge ports and may lead, for instance, to a low pressure gas reservoir which is fitted with means forrepressuring the *gas and returning it to the high pressure gas- 25 line or to any-other suitable point in the system.

The valve 35 is connected by means of stem 33 to a diaphragm 34 which is installed in such relationship with the eduction tube at the well head that it is actuated either directlyv or indio rectly, for example, through means of a level controller having for example, a float placed in the eduction tube and adapted to bear against the diaphragm, by the pressure of the liquid rising in the eduction tube I. The diaphragm 34 35 lg preferably placed transversely in the bore of the eduction tube adjacent and above the point at which the discharge line III is connected thereto. A chamber 35 formed above the diaphragm is connected to the discharge line l by 40 means of line 35 provided with a valve 31 for a subsequently described purpose.

As referred to above, the supply of pressure gas to the tank 2| may be intermittent, and for this purpose the needle-valve 24 is closed, and

45 the line 22 is connected to the high pressure line l by means of line 40 carrying a spring-loaded valve 4| provided with a spring 42 and with a projecting stem 43. Cams 44 on a rotating disk 45 periodically contact the stem 43 and force the 5 valve 4| open.

Now referring to Figures 11 and III of the drawing, a plurality of such disks 45, each controlling the operation of a separate gas-lift pump, may be arranged on a shaft 50 which is 55 rotated by any suitable means, such as, for example, electrical or mechanical driving devices. However, when it is desired to avoid the necessity of an auxiliary prime mover, as may be the case in remote places or for economy, the shaft 0 50 may be caused to rotate by the rise and fall of a float having associated therewith means for translating the reciprocating motion of said float into rotary motion of the shaft 55. In a preferred form a toothed wheel 5| may be carried 5 by the shaft 53 or, as shown, operatively connected to the shaft 53 by suitable gears, such as, for example, cooperating gears 52a coaxially attached to the toothed wheel 5| and 52b fastened to the shaft 50. The toothed wheel is actuated 70 by the rise and fall of a float 53 carrying a vertical shaft 54 which is provided at its upper end with a spring-loaded pawl arrangement 55 adapted to engage the toothed wheel 5| during the downward travel of the shaft 54. The float 75 53 is caused to rise and fall by the fluctuating level of a liquid in a float container 56 as shown. A conduit 51 provides liquid communication between the lower portion of the float container 56 and the lower portion of a chamber 53, containing means for reciprocating the liquid level 5 therein and consequently the liquid level in the float container 56. For this purpose, pressure gas is continuously admitted to the upper portion of the chamber 53 from a conduit 53 attachedthereto and provided with a throttled orifice, such as a needle valve 60. A valve III in the upper portion of the chamber 53 is carried by a rod ll extendinginto the chamber and guided by a spider 12. Between spaced stop members 13a and 13b attached to the valve rod 1| and fitting slidl5 ingly about the rod II is a float I4, which may be of any suitable form and construction, such as an anally perforated cast iron disk when mercury is used. Vertical rods may be spaced in sliding relationship to the float 14 to align the float and thereby insure proper axial alignment of the valve rod II and valve III or the rods 15, or any other suitable guiding means may be so spaced about the stop members 13a and 131) if these be of a larger diameter than the'float I4.

The operation of the apparatus of the present invention is as follows: Starting with the valve l6 (Figure I) closed and well liquid accumulating in the displacement chamber 5, pressure gas is admitted through valve 24 or 4| and line 22 to the tank 2|. After some time the pressure built up in the tank and acting upon the diaphragm 20 in the wall thereof is suiflcient to overcome the combined action of the gas pressure in conduit I5 and the valve spring l8, and the outward movement of the diaphragm 20 causes the valve l5 to open so that pressure gas flows through the gas supply pipe 8 and down the annular. space 9 to the displacement chamber 5 and forces the liquid up the eduction tube I.

both sides of the diaphragm 34 and the valve 30 is opened-solely by the impact of the rising liquid. By thus opening the valve 30, gas escapes 5 from the tank 2| through the ports 39 to the atmosphere, decreasing the pressure on the diaphragm 20, whereby thevalve I8 is allowed to close by the action of its spring l8 thus shutting oil the gas supply line 8.

Then the gas present in the line 8 and the annular space 9 expands, thereby further lifting the liquid in the eduction tube I, and finally escapes through the discharge line I0. Due to the decrease in pressure of the fluid on the dia- 60 phragm 34, the discharge valve" is caused to close by the action of its spring 32 and another period of pressure rise in tank 2| commences.

To facilitate the escape of gas still remaining in the displacement chamber and the lines connected thereto after the raising of the liquid, suitable release valves may be provided in the gas supply pipe 8 and/or the discharge line It, if so desired.

Other constructions are, of course, possible 1.0

and instead of the valves l6 and 30 as shown in Figure I it will, for example, be possible to use balanced valves.

If a number of the described individual gas"- lift pump controls are used at short distances ('5 from each other, the gas supply to the separate tanks 2| may be controlled by means of the cam disks 45, each actuating a valve 4|, as stated above. In the operation of the float-operated gear means comprising the disks 45, as shown in Figure II, gas from the high pressure system is admitted by means of conduit 59 and accurately adjusted needle valve 60 into chamber 58. The liquid level therein is depressed by the gas pressure, causing the float 14 to descend about the valve rod ll until it rests on the lower stop member 13b. The weight of the float 14 on the stop member 13b attached to the valve rod H causes the valve 10 to open, allowing the gas to escape from the chamber 58. The pressure in the chamber 58 thus being decreased, the liquid level therein rises along with the float 14 which subsequently abuts the upper stop member 13a and thus closes the valve l0. Then another cycle of pressure accumulation and liquid level depression is started.

The liquid level in the float container 56 is caused to fall and rise as an inverse function of the rise and fall of the liquid level in the chamber 58 to which it is connected by means of conduit 51. These variations of the liquid level in container 56 cause the reciprocation of the float 53 and the shaft 54 attached thereto. As the pawl arrangement 55 on the upper end of the shaft 54 is adapted to engage the toothed wheel 5| on the downward stroke of the shaft 54, the toothed wheel 5| and the shaft 50 connected thereto by means of gears 52a and 52b is caused to turn by the weight of the float 53 attached to the shaft 54.when the level in the container 56 falls as a result of the gas escaping from the chamber 58. By close adjustment of the needle valve 60, the speed of rotation of the cam disks 45 can be accurately regulated.

I claim as my invention:

1. In an intermittent gas-lift device, a source of supply of gaseous pressure, a pressure gas reservoir, a reservoir for the liquid to be lifted, a liquid eduction tube extending into the liquid reservoir, a conduit between the source of supply and the gas reservoir for gradually building up pressure in said reservoir, a conduit between the source of supply and the liquid reservoir, a spring controlled valve normally closing said conduit, means responsive to a predetermined pressure in the gas reservoir to open said valve, a normally closed valve in communication between the gas reservoir and a zone, of low pressure, and impact means actuated by the flow of the liquid rising in the eduction tube to open said valve.

2. The device of claim 1, comprising an adjustable metering valve in the pressure conduit to the pressure gas reservoir for continuously.

supplying gas to said reservoir at a desired rate. 3. The device of claim 1, comprising a valve in the pressure conduit to the pressure gas reservoir, and prime-mover means for periodically opening said valve.

4. The device of claim 1, comprising a valve in the pressure conduit to the pressure gas reservoir, rotatable cam means for periodically opening said valve means, and means to rotate said cam means.

5. The device of claim 1, comprising a valve in the pressure conduit to the pressure tank, rotatable cam means for periodically opening said valve, rotatable gear means adapted to actuate said cam means, a closed vessel partially filled with liquid, means for alternately raising and lowering the liquid level in said vessel, a float supported by said liquid, and link means between said float and said gear means whereby the reciprocating motion of said float is translated into a rotational motion of said gear.

6. In an intermittent gas-lift system, the combination of a plurality of devices each comprising a pressure gas reservoir, a reservoir for the liquid to be lifted, conduits adapted to supply pressure gas to said reservoirs, an eduction tube extending into the liquid reservoir, a valve in the pressure conduit to the liquid reservoir, spring means normally closing said valve, means responsive to a predetermined pressure within the pressure gas reservoir adapted to open said valve, a valve in communication between the pressure gas reservoir and a low pressure zone, impact means actuated by the flow of liquid in the eduction tube adapted to open said valve, a valve in the pressure conduit to the gas reservoir, and rotatable cam means for periodically open ing said valve, with a single gear means adapted to actuate the cam means of said devices, a closed vessel partially filled with liquid, a source of pressure gas in communication with said conduits and said vessel, means for alternately raising and lowering the liquid level in said vessel, a float supported by said liquid, and link means between said float and said gear means whereby the reciprocating motion of said float is translated into a rotational motion of said gear.

7. In an intermittent gas-lift device, a source of supply of gaseous pressure, a pressure gas reservoir, a reservoir for the liquid to be lifted, a liquid eduction tube extending into the liquid reservoir, a conduit between the source of supply and the gas reservoir for gradually building up pressure in said reservoir, a conduit between the source of supply and the liquid reservoir, a spring controlled valve normally closing said conduit, means responsive to a predetermined pressure in the gas reservoirto open said valve,

a normally closed valve in communication be-.

tween thegas reservoir and a zone of low pressure, diaphragm means in the upper portion of the eduction tube actuated by the flow impact of the liquid rising in the eduction tube to open said valve, and a liquid conduit in communication between the two sides of said diaphragm for equalizing the static pressures on either side of said diaphragm.

' 'ALEXANDER-WEHELMUS STEENBERGH. 

